The broad, long-term objective of this proposal is to use autoantibody profiling to guide the selection of DNA tolerizing vaccines for the treatment of an animal model of primary biliary cirrhosis (PBC) called experimental autoimmune cholangitis (EAC). We will test the hypothesis that large-scale, parallel detection of autoantibody profiles can be used to explore epitope spreading, the role played by a subset of inflammatory cytokines in the initiation and propagation of autoimmunity, and ultimately in selection of antigen-specific tolerizing therapies. We will use biochemical, immunological, and molecular biological techniques to validate and extend our ongoing protein array platform in exploring three specific aims in this proposal: (i.) to construct a PBC autoantigen microarray suitable for the identification of human and murine autoantibodies. This array will be used to identify dominant B cell epitopes in the EAC model, and to determine the precise ordering of epitope spreading in EAC. (ii.) to determine whether interleukin-4 (IL-4) and interferon-gamma (IFNy) are required for the development of EAC. An imbalance between Thl and Th2 lymphocytes is thought to play an important role in some autoimmune diseases, and IL-4 and IFN3' represent critical cytokines in the pathogenesis of autoimmunity. (iii.) to employ DNA vaccination to prevent and treat EAC using cDNAs encoding autoantigens identified using protein microarrays developed in the first aim. The results of this proposal will determine the long-term usefulness of the newly described EAC animal model of PBC. Successful treatment of EAC using plasmids encoding prominent autoantigens may herald an era of customized, antigen- or tissue- specific tolerizing therapy in humans.